Evidence on the macroscopic length scale spin coherence for the edge currents in a narrow HgTe quantum well
A. Kononov+, S. V. Egorov+, Z. D. Kvon*×, N. N. Mikhailov*, S. A. Dvoretsky*, E. V. Deviatov+
+Institute of Solid State Physics of the RAS, 142432 Chernogolovka, Russia
*Rzhanov Institute of Semiconductor Physics SB of the RAS, 630090 Novosibirsk, Russia
×Novosibirsk State University, 630090 Novosibirsk, Russia
Abstract
We experimentally investigate spin-polarized electron transport between two
ferromagnetic contacts, placed at the edge of a two-dimensional electron
system with band inversion. The system is realized in a narrow (8 nm) HgTe
quantum well, the ferromagnetic side contacts are formed from a
pre-magnetized permalloy film. In zero magnetic field, we find a significant
edge current contribution to the transport between two ferromagnetic
contacts. We experimentally demonstrate that this transport is sensitive to
the mutual orientation of the magnetization directions of two
200 μm-spaced ferromagnetic leads. This is a direct experimental evidence on the
spin-coherent edge transport over the macroscopic distances. Thus, the spin
is extremely robust at the edge of a two-dimensional electron system with
band inversion, confirming the helical spin-resolved nature of edge currents.